Unstable (reactive) materials stored in quantities greater than 500 cubic feet (14 m3) shall be separated into piles, each not larger than 500 cubic feet (14 m3). Aisle width shall not be less than the height of the piles or 4 feet (1219 mm), whichever is greater.

Outdoor storage of Class 4 or 3 (detonable) unstable (reactive) material shall be in accordance with Table 5604.5.2(2). The number of pounds of material listed in the table shall be the net weight of the material present. Alternatively, the number of pounds of material shall be based on a trinitrotoluene (TNT) equivalent weight.